The operational range of a system that combines and distributes signals within buildings or other areas where wireless signal propagation is likely to be a problem, whether the signals are digital or analog or some combination of both, is limited by the dynamic range handling capability of the system. Background noise effectively limits the dynamic range of a system. In a distributed system, such as the one disclosed in U.S. patent application Ser. No. 09/619,431, “Point-To-Point Digital Radio Frequency Transport,” filed on Jul. 19, 2000 (Attorney Docket No. 100.019US01), incorporated herein by reference as if fully set forth, signals of varying levels as well as background noise, are present at input ports, at signal combiners and at output ports. When combining signals from various antennas and other input ports and remote units, with or without individual amplifiers, the noise floor of the system generally increases by 10 log N, where N is the number of signals being combined. The problem is exacerbated when signals are combined from RF receivers that each have a given noise figure and the combined signals may contain aliases, images and spurs of the background noise due to sampling effects, frequency translation and the like. If such signals are combined in a purely additive way without regard to whether any useful information is present, the overall noise performance of the system will suffer. It would thus be desirable to intelligently select input signals so that overall system noise may be reduced.
The above-mentioned problems with noise performance in distributed communication systems within buildings and other enclosed areas, as well as other problems, are addressed by the present invention and will be understood by reading and studying the following specification.